Ericsson Engine
Oh yeah!
It is not a new project of that similar name smart phone company! :P
This caloric engine has mechanical controlled valves, a "2 in 1" piston,
A cold compression area, regenerator,
but only one power stroke.
Patented in 1853.
The engine has an ideal cycle what we call Ericsson cycle.
The cycle's steps are:
Isothermal compression, isobaric heat addition, isothermal expansion, isobaric heat rejection.